function ke = function_of_ke(JXe)
%% 初始化 ke
ke = zeros(3, 3);

%% 定义数值积分参数
kesi = [0.932469514203152, 0.661209386466265, 0.238619186083197, -0.932469514203152, -0.661209386466265, -0.238619186083197];
w = [0.171324492379170, 0.360761573048139, 0.467913934572691, 0.171324492379170, 0.360761573048139, 0.467913934572691];

for i = 1:6
    %% 插值函数对kesi的导数, 式(1.47)
    dfy_dkesi = [kesi(i)-1/2;
        -2*kesi(i);
        kesi(i)+1/2];
    %% Jacobi 相关计算
    dx_dkesi = dfy_dkesi' * JXe; % 式(1.57)
    J = dx_dkesi; % 式(1.55)
    invJ = inv(J);
    dfy_dx = dfy_dkesi * invJ; % 式(1.54)
    %% ke 计算
    ke = ke + w(i)*(dfy_dx*dfy_dx')*det(J); % 式(1.62)注
end

end